We are investigating metalloenzymes that catalyze steroid hydroxylations, nitrogen and nitrate reduction, and glutamate metabolism in a variety of organisms. Our principal approaches are: (a) the isolation of homogenous enzyme systems (b) characterization of these enzymes by metal analysis and protein chemical techniques, as well as by EPR spectroscopy of various oxidation states (c) kinetic studies using both classical steady state methods and pre-steady state (stopped flow and freeze quench) methods (d) studies in whole cells and tissues of the in vivo condition of these enzymes, principally by magnetic resonance methods. We wish to understand the catalysis of oxidation-reduction reactions at the molecular level, their control in metabolic systems, and their conditioning by humoral and other extracellular factors. BIBLIOGRAPHIC REFERENCES: Jefcoate, C.R., and W.H. Orme-Johnson. Cytochrome P-450 of Adrenal Mitochondria. In vitro and in vivo Changes in Spin States. J. Biol. Chem. 250, 4671-4677 (1975). Munck, E., H. Rhodes, W.H. Orme-Johnson, L.C. Davis, W. Brill, and V.K. Shah. Nitrogenase VIII. EPR and Mossbauer Spectroscopy. Properties of the MoFe Protein of A. vinelandii Nitrogenase. Biochim. Biophys. Acta. 400, 32-53 (1975).